This is so bang on, i remember a Compressor [ new V4 ] it was clattering after a few hrs running, we whipped off the heads, and there was a nut jammed between the valve plates, left in by the factory builders, We also dropped the oil after 100 hrs . and did an acid test to show any traces of metals in oil, thats the reason of running in new engines,
increase the revs a bit groucho, just dont hold it flat out,,
I remember running in our 2 strokes , they wouldn"t rev out when time came to cane them,, smoked like hell too..